WHEN USALS WON'T WORK

   One of the frequent items of discussion relative to small motorized offset dish systems, is USALS vs DiseqC-1.2 , particularly with respect to situations when USALS doesn't seem to work.  I've seen many posts involving situations where people say that USALS seems to take their dish to a point where all the satellites seem to be off  just a bit, and can be tuned in by using the DiseqC-1.2 bump commands.   The question is,  is this symptom proof that the system is out of alignment?    NO.  It can also be an indication of a system that is simply out of sync for some reason.

     Basically, there are two issues here.  A properly aligned dish, is one which the motor will follow the Clarke belt across the sky.  An out of sync dish, is one which, which follows the clarke belt, but stops at positions that are just slightly off for each satellite.  It is possible that being off slightly on each sat can be caused by improper alignment, but it is not by itself indicative of improper alignment.

   If everything in the system is perfect, then, in theory, USALS will not result in an out of sync situation, mainly because the first step of the alignment process, ie peaking on your true south sat, is largely a re-sync step.  However few small dish systems are perfect.

   So what will cause an otherwise perfectly aligned sat system to be out of sync, and not work properly with USALS? 
  (1) One thing, is a motor, which hasn't been calibrated properly at the factory, and doesn't come back to zero when the goto-zero or goto reference command is received.  My SG2100 motor would go to a position that was about 2 degrees west of zero when I'd send it a goto-zero command.  If this is the case, USALS will be out of sync even on a PERFECTLY ALIGNED SYSTEM.  This is because USALS is completely dependent on "zero" being "south".  If the motor isn't calibrated properly at the factory, zero will be off, and USALS will be off by that amount if the system is aligned properly.
  (2)  Similar to the above, if your lnbf arm isn't centered properly, ie aiming south when the dish is aiming south, then the same thing will happen.  Ie when the motor is at it's zero position, the dish may be aiming a degree or so away from south, even if the dish is perfectly aligned.  This can be caused by the LNBF arm being slightly bent, or from the bolts which attach it to the dish having been tightened wrong, or from the dish being slightly warped.  On my brand new dish, the lnbf arm was over 2" away from the true focal point. This will result in a situation where when the motor is at zero, the dish isn't aiming at zero, and USALS won't work.
  (3)  Of course, the third possibility, is that the system is out of alignment, most likely with respect to the alignment of the whole mount on the pole.  Ie if the mount is shifted to the east or west on the pole, then when the motor is at it's zero position the dish will be aiming east or west of south, and all the positions will be a bit off. 

   The question and problem is, however, how to tell which of the above is the case?  Basically, you want to determine whether, as in (3), your system is out of alignment.  You do this by going to the sat via motor, then peaking as best possible on the sat by bumping the motor east/west.  Then, out at the dish see if lifting/pulling down, in different directions will improve your signal.  If all actions result in degradation of the signal, then, you were on the Clarke belt, and the out of sync situation was probably not due to being out of alignment.  However, the above should be tried on a few different sats.  But, if you can't improve your signal by the lift/pull actions after bumping with the motor, then attempts to re-align will be of no help, and may make things worse.

   If (3) has been eliminated, and you think you have simply a situation of an out of sync system, then what can be done?
Well obviously, one thing that can be done is to use DiseqC-1.2 instead of USALS.  DiseqC-1.2 isn't as user friendly as USALS, but really gives you more control over your system if you can learn to use it right.  Another option is to use USALS, however experiment a bit with the setting for your longitude.  Often if you alter your location's longitude setting a bit, it can in effect shift the USALS positions so that all will line up properly. 

   There are 2 other actions which MAY help in some situations, however I haven't tried either, so I'm not positive.  One is, if your motor came calibrated wrong, so that it doesn't center when sent to zero, some motors allow you to manually bump the motor to it's true zero position, then do a hardware reset, thus calibrating the motor.  I THINK this will work, but as I said, I haven't tried this.  The other similar thing that MIGHT help, is the DiseqC-1.2 "resync" command which most true DiseqC-1.2 receivers can send. To do this, I would send the dish to a sat via USALS, then using DiseqC-1.2 (hopefully without it moving to another position, which some receivers do),  first SAVE that position as the DiseqC-1.2 position, then bump the motor to peak that satellite, THEN send the DiseqC-1.2 RESYNC command.  This should shift all sat positions by the same amount.  I am not sure whether this will also re-set the zero position on the motor or not, but there is a possibility that it might. If it does, then it should resync the system for USALS as well, but if it doesn't, then it will only affect DiseqC-1.2 operation.   It's worth a try though.

   Anyway, the bottom line is that having a system in which USALS requires bumping the motor to peak the sats is NOT by itself proof that your system is out of alignment.  That is only one of 3 possible reasons for this symptom.  And if you are basically seeing ALL the sats, but are off by a bit on all, then it is most likely that you just have a system that is out of sync, not out of alignment.



Addendum:
   There is still some skepticism about this.  As added proof, consider the following:

One way to think about it is to consider an EXTREME situation, ie say the motor is off by 30 deg to the east.  Ie the motor axis and the bend in the shaft will be rotated 30 degrees. 
   Normally when you align a small offset dish, you first use USALS to goto your southern sat.  Say this sat is 1 degree west of your true south.  Ok, now the motor will go to 29 deg east of where it should go.   If you find your true south using what the motor perceives as true south, then turn to the next sat to the west say, the dish will move higher in the sky, even though the true south sat is always highest. Ie the system is WAY out of alignment because you've had to use incorrect dish or motor elevations to reach that south sat.
    In this situation, you'll probably only be able to locate that one sat.  Now, however, assume that you are able somehow to correctly align the system.  Proper alignment is when the bend in the motor shaft is aimed down, when aimed at or near your true south sat.  To get the motor to this point, you'd have to run the motor 30 deg to the west. 
 Once aligned properly, your motor will be following the arc properly, but you'll be seeing your true south sat some 30 deg west of where USALS thinks south is. {Not sure that was said clearly.} Basically, what I'm saying is that for proper alignment, your true south sat needs to have been found with the motor centered on it's true zero, however USALS will be calculating vs what the motor perceives as zero.  If you now give the motor a USALS comand to go to your true south sat, it will again go to 29 degrees to the east, instead of 1 degree to the west.  Ie in this situation with an out of sync motor, USALS cannot possibly work.

   Now I understand that the above example is EXTREME.  Most out of sync situations will be MUCH smaller.  My motor was out only a degree or two.  However the principle is the same regardless of the magnitude of the error.  Even with a 1 degree out of sync motor, USALS will be off by 1 degree on ALL satellites, unless you lie to your receiver with respect to what your longitude is by 1 degree. 

   Additional info.  There was a recent post by another Sadoun forum member indicating that the motor reset (hardware I think) does work to correct this situation.